Masticatory muscle thickness, bite force, and occlusal contacts in young children with unilateral posterior crossbite

Abstract

Few investigations have evaluated the characteristics of functional and structural malocclusion in young children. Thus, the aim of this study was to assess the ultrasonographic thickness of the masseter and anterior portion of the temporalis muscles, the maximum bite force, and the number of occlusal contacts in children with normal occlusion and unilateral crossbite, in the primary and early mixed dentition. Forty-nine children (26 males and 23 females) was divided into four groups: primary-normal occlusion (PNO), mean (PNO) age 58.67 months; primary-crossbite (PCB), mean age 60.50 months; mixed-normal occlusion (MNO), mean age 72.85 months; and mixed-crossbite (MCB), mean age 71.91 months. Thickness was evaluated with the muscles at rest and during maximal clenching, and comparison was made between the right and left side (normal occlusion), and between the normal and crossbite side (crossbite). The results were analysed using Pearson's correlation, paired and unpaired t-test, and Mann-Whitney ranked sum test. The anterior temporalis thickness at rest was statistically thicker for the crossbite side than the normal side in the MCB group (P = 0.0106). A statistical difference in bite force and the number of occlusal contacts was observed between the MNO and MCB groups, with greater values for the MNO subjects (P < 0.05). Masseter muscle thickness showed a positive correlation with bite force, but the anterior temporalis thickness in the PCB and MCB groups was not related to bite force. Masticatory muscle thickness and bite force did not present a significant correlation with occlusal contacts, weight, or height. It was concluded that functional and anatomical variables differ in the early mixed dentition in the presence of a malocclusion and early diagnosis and treatment planning should be considered.

Relationship between maximum bite force and the gonial angle in crossbite

“…When we searched for crossbite, the focus of this study, we found many studies in children with proved functional alteration, exemplified by the reduced bite force [5,[14][15][16][17][18]; however, limited evidence has been found in adults for this specific malocclusion.…”

“…Studies in children have demonstrated less electromyographic activity on the cross side during mastication [4], muscle atrophy visualized by ultrasonography (US), and decreased MBF [5].…”

Avaliação do dimorfismo sexual e da relação entre as características craniofaciais, dos arcos dentários e do músculo masseter na fase de dentição mista

“…The use of both intercanine distance between cusp tips and between cervical points is justified because the latter distance is more reliable and less susceptible to tooth inclination. But the use of ultrasound in scientific research provides reproducible and easy access to the masticatory muscles thickness, obtaining quantitative information on functional ability and determination of structural changes 17 , without the subject's exposure to radiation.…”

“…The transducer was placed perpendicular to the muscle fiber direction, using an air-tight inert gel on the skin surface, and moved gradually to obtain optimal visualization 17 .…”

“…Thus, the use of accurate and reproducible methods for measuring craniofacial anatomical structures is the best way to understand the interplay between form and function [15][16][17] .…”